Relatively large numbers of persons suffer from a variety of respiratory diseases. Three main respiratory diseases are bronchitis, emphysema and asthma. In two of these, the airways of the lungs become constricted and breathing becomes labored or difficult. To some extent, the conditions caused by bronchitis and asthma are reversible. Inhaled medications have been developed to provide fairly rapid relief from the symptoms of bronchitis, emphysema and asthma. These medications typically are dispensed from hand-held, metered multi-dose inhalers, which deliver medications for dilating the airways of the lungs and/or for reducing the swelling of inflammatory allergic tissues of the airways. Such medications are sold under a number of different brand names.
Most hand-held inhalers include a pressurized aerosol container for the medication. The container then has a metered pressure-actuated outlet on it, which is coupled with an atomizer nozzle. The atomizer nozzle, in turn, directs the atomized medication spray into a mouthpiece, from which the medication is sprayed into the mouth of the user for inhalation into the lungs.
Almost all of the hand-held dispensers utilize the same operating principle described above, and are subject to the same limitations. A primary problem is that the medication is sprayed into the mouthpiece at a relatively high velocity and in a fairly narrow concentrated stream. A major percentage of the medication, which is sprayed through such a dispenser, is deposited in the mouth, throat and trachea of the user. Eventually, this deposited medication is swallowed; but such medication deposits do not reach the lungs where the medication is required. Consequently such deposited medication serves no medical purpose to the patient, and may additionally result in undesirable side effects and expense.
Since only a relatively small percentage of the overall medication which is released in a conventional hand-held, metered dose inhaler is applied to the airways and the lungs, more frequent application of medication is required. This, in turn, compounds the undesirable side effects of the deposited medication mentioned above. These problems are particularly aggravated for children and the elderly, who may have difficulty in coordinating the release of the medication and inhalation for most effective use.
Efforts have been made to improve the effectiveness of metered dose inhalers by providing a spacer between the standard mouthpiece of the inhaler, as sold, and the mouth of a user. Such devices are shown in the U.S. patents to Zoltan U.S. Pat. No. 4,926,852 and Walstrom U.S. Pat. No. 5,178,138. Both of these patents are directed to delivery devices in which a metered dose inhaler canister itself is inserted into a receptacle, which causes the dose to be directed away from the mouth of the user into a chamber, from which the aerosol spray is withdrawn by the user in a direction opposite to the direction the dosage is sprayed into the chamber.
The structure disclosed in the Zoltan patent is the simpler structure of these two delivery devices. In Zoltan, to permit air to be drawn through the spacer and out through the mouthpiece, air inlets are provided in the end of the spacer opposite from the end in which the medication is admitted. This is done by a series of small perforations and by means of a generally truncated cone, which helps to baffle the sprayed agent and to mix the agent with air which is admitted into the chamber when a patient withdraws air from the mouthpiece. In both of these devices, the medication canister itself is removed from the remainder of the inhaler devices, which are normally sold as a unit with the canisters. The devices of both Walstrom and Zoltan are relatively complex in configuration, and require incorporation of an atomizer nozzle as part of their construction. Thus, the atomizer nozzle which normally is supplied with the mouthpiece of the metered dose inhaler is wasted or discarded.
Two other types of spacers, which do not require an atomizer nozzle and which operate in line with the conventional mouthpiece of a standard metered dose inhaler, are described in the U.S. Pat. Nos. 4,470,412 and 4,953,545. The devices of both of these patents operate in a similar manner; although the one disclosed in U.S. Pat. No. 4,953,545 is of a simpler configuration than the device disclosed in the '412 patent. The devices of both of these patents are in the form of elongated cylindrical chambers. In patent '545 the device is simply a hollow canister; while the device of patent No. '412 includes additional features, such as a filter and a whistle in the multiple part assembly. To accommodate the mouthpiece end of different types or shapes of dispensers, both of these devices have the inlet end closed with a resilient plastic material having an aperture in the center of it. The material of the aperture is made sufficiently soft to stretch and conform around the shape of different inhaler mouthpieces. Consequently, in constructing the devices of both of these patents, the provision of the resilient aperture for receiving the various shaped mouthpieces means that this portion of the device must be made of a different material from the more rigid canister forming the main body of the spacer. As a consequence, this part needs to be separately manufactured and installed. This results in increased manufacturing costs. In addition, the resiliency of the aperture end of these devices permits misalignment of the mouthpiece, which could direct medication onto the wall of the spacer instead of into the center of the spacer chamber. This would waste the medication.
Another spacer for metered dose inhalers is disclosed in "Advances in Therapy", Vol. 10, No. 5, Sept/Oct 1993, on Page 209. The device disclosed in this article is a generally circular shaped housing which accommodates a pressurized aerosol canister at one side. The aerosol canister or dispenser must be removed from the atomizer and mouthpiece with which it normally is sold, and inserted into the spacer device. As a consequence, the spacer requires the inclusion of an atomizer in it. This nozzle is inserted between two polypropylene shells which, in turn, shape the round expansion chamber. Upon actuation and prior to inspiration from a mouthpiece opening opposite the diffuser nozzle, the emitted particulate stream is forced into a spiral. The expansion chamber creates a whirling flow of expelled particles, which are intended to remain suspended long enough to expend their kinetic energy.
Other spacers, specifically directed to a particular type of device with which they are used, are disclosed in the U.S. patents to Hansen U.S. Pat. No. 3,994,521; Lehmbeck U.S. Pat. No. 4,253,468; and Tritle U.S. Pat. No. 5,203,323. None of the devices disclosed in these three patents are directed to any type of "universal" accommodation for the mouthpiece portion of an otherwise standard inhaler to accommodate different shapes of mouthpieces. All of these devices are relatively complex in configuration.
It is desirable to provide an inhaler spacer which is capable of use with different shaped mouthpiece portions of commercial, standard inhalers, which is simple in configuration, compact easy to use, and relatively inexpensive.